Shock preventer for clamshell buckets



y 6, 1933,- w. M. VENABLE 1,909,081

SHOCK PREVENTER FOR CLAMSHELL BUCKETS Filed Dec. 29, 1930 3 Sheets-Sheet 1 May 16, 1933. w. M. VENABLE SHOCK PREVENTER FOR CLAMSHELL BUCKETS Filed Dec. 29, 1950 3 Sheets-Sheet 2 May 16, 1933. w. M. VENABLE SHOCK PREVENTER FOR CLAMSHELL BUCKETS Filed Dec. 29, 1930 3 Sheets-Sheet 3 r i i I ks W INVENTOR I: .4 IP27, I

( ATTORNEYS n "u E. d I

Patented May 16, 1 933 UNITED STATES. PATENT OFFICE \NILLIAZM MAYO VENABLE, OI PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO BLAW- KNOX COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION 01 NEW JERSEY SHOCK PREVENTER FOR CLAMSHELL BUCKETS Application filed December 29, 1930. Serial No. 505,273.

This invention relates to excavating buckets, sometimes referred to as grab buckets or clamshell buckets, audit is particularly ap plicable to that type of bucket which is known as the single line bucket in which opening and closing of the bucket, as well as lifting or hoisting thereof, is accomplished by means of a singlefcable. A bucket of this type is disclosed and claimed in my prior Patent No. 1,258,833, issued on March 12, 1918, to which reference can be made if so desired.

The primary object of the present invention is to provide means for greatly increasing the safety factor in operating a bucket of this kind, not only with respect tothe bucket itself, but also with respect to the line and the crane used in its operation. This object is accomplished by the provision of suitable shock absorbing mechanism adapted "to cushion sudden upward movement of the hinge block such as occurs, for example, when the bucketis opened while suspended on its operating line but with the scoop segments.

not quite in their fully closed position due to the presence of a lump of hard material between the lips of the scoops.

It is a further object of the invention to provide a shock absorbingmechanism which will not appreciably retard or interfere with a normal closing operation nor impair or detract from the closing power of the cable.

Still another object of the invention is to construct the shock absorbing mechanism above described in such a way as to enable it to perform the additional function of a stop for limiting the upward movement of the hinge block.

Stated in more detail, it is the object of my invention to provide a dashpot mechanism for the purpose described which is suitably pivoted to the bucket head and'provided with positioning means for ensuring proper contact with the hinge block as the latter is brought upwardly toward the bucket head during a closing operation.

The foregoing objects, together with such other objects as may appear hereinafter, or are incident to my invention, are attained by -means of a construction which is illustrated in a preferred form in the accompanying drawings, wherein Fig. 1 is aside elevation of a singleline bucket embodying my improvements, with the scoop segments in the position they would occupy while suspended from the operating cable, although not quite in their fully closed position due to the presence of a piece of stone or some other hard substance between the cutting edges of the scoops, the condition here illustrated being a common one in the operation of buckets of this type.

Fig. 2 is a view similar to that of Fig. 1 showing the parts shortly after the bucket has been tripped in order to open it, but before the scoops have had an opportunity to open appreciably.

gig. 3 is a section on the line 33 of an Fig. 2,

- Fig. 4 is an enlarged section taken on the line 44 of Fig. 3. I

By referring to the drawings, it will be seen that the bucket scoops 5 and 6 are hinged together in the customary manner upon the hlnge pin 7, and that the upper outer corners of the scoops are supported by means'of the corner bars 8 and 9 pivoted to the scoops on the pins 10 and 11 respectively. The bars 8 at one side of the bucket are pivoted at 12 to the bucket head construction indicated as a whole by the reference character 13. The bars 9 are of composite structure, the details of which it is not'necessary to consider because they form no part of the present invention, but it will be noted that the bars 9 are rigidly secured to the bucket head, in which latter is mounted the head block 14 carrying the head sheaves 15.

The lower or hinge block 16 is securedto the radius bars 17 which are pivoted to the scoop 6 on the same axis as the corner pins 11.

The operating line or cable 18 passes down through the head construction 13 and is reeved between the sheaves 19 in the hinge block and the sheaves in the head block pending application Serial No. 496,900, filed November 20, 1930. The other end of the cable 18 (not shown) is, of course, connected to the operating crane.

The lower or hinge block 16 is maintained in fixed relationship with the hinge 7 by means of the folding arms 21 and 22 when the latter are in their closing position shown in Fig. 1. The hinge 7, however, can be dropped and the bucket thereby opened by tripping or unfolding the arms, their position being shown at an early stage in the opening operation of the bucket in Fig. The function and operation of the folding arms 21 and 22 is now well understood in this art, and since this feature forms no part of the present invention, it will not be described in any greater detail, but, if desired, reference may be had to my prior patent above mentioned, which contains a complete disclosure of the method in which a bucket of this type is operated.

It should be noted, however, that my invention is not to be limit-ed to a construction of this particular kind, as it might be applied equally well to some other type of single line bucket, the type shown and described being for illustrative purposes only.

The invention claimed in the present ap plication relates to the shock absorbing mechanism by which the lower block 16, when in the position shown in Fig. 1, is cushioned or retarded in its motion to the position shown in Fig. 2, either as a result of tripping the bucket so that the arms 21 and 22 will unfold and permit the bucket hinge 7 to drop,

or as the result of the breaking or slipping of a lump of material which may have been preventing the scoops from closing entirely.

It will be understood, of course, that under circumstances where the bucket is suspended upon the cable 18 with the scoops 5 and 6 not quite in their fully closed position be cause of the interposition of some foreign object, such as a piece of rock or lump of other hard material 23 between the cutting edges or lips 24 and 25 of the scoops, the hinge block 16 will not yet have reached its extreme upright position. If, now, under these conditions, the bucket were to be tripped and the arms 21 and 22 permitted to unfold so as to lower the hinge 7 and open the scoops 5 and 6, or if the lump 23 were to break or slip from its position, the block 16, under the effect of the weight of the bucket and its load, would immediately move up with great violence, particularly in the larger type buckets which may weigh as much as several tons or mor This motion of the block 16, of course, permits the bucket as a whole to lower itself until the slack in the lines produced by the sheaves in the head block 4, is taken up. The violent impact of the'hinge block 16 with the head construction 13 and the dropping of the bucket until the lines are again taut would impose a shock not only upon the bucket structure itself, but also upon the cable and the operating crane, which is so severe as to be not only extremely hard upon the structure of the bucket, but also very dangerous because of the liability of breakage and dropping of the bucket.

By means of my improvements now to be described I provide for retarding or cushioning the motion just described, as well as for definitely limiting it.

Between the bucket head 13 and the hinge block 16 I provide a dashpot mechanism 26, the piston 27 of which is secured to the bucket head construction by pivoting its rod 28 upon a pin 29 in the bucket head. The cylinder 30 of the dashpot mechanism is held in its proper position by means of the hanger 31 pivoted at its lower end to a suitableear or cars 32 on the cylinder and at its upper end to the head 13 upon the pin 33, the hanger 31 being provided with a slot 34 for embracing the pin 33 in order to permit the necessary upward movement of the hanger as the hinge block 16 comes to its final position shown in Fig. 2.

I prefer to include in the hanger construction a threaded member 35 which screws into the portion 31 in order to provide a means for adjusting the position of the cylinder 30.

Also pivoted to the cylinder at the cars 32 is a thrust rod 36 pivotally connected at its other end 37 to the head construction 13, preferably at a point between the pivots 29 and 33. The rod 36 is forced downwardly by the spring 38 reacting between the collar 39 and the adjustable nut 40. The thrust rod, therefore, will assist gravity in pushing the cylinder down to its lowermost position when the hinge block 1.6 is not in contact therewith through the medium of the parts now to be described.

At the lower end of the cylinder there is a recess 41 in which fits a roller 42 held loosely in place by means of the bolt or pin 43. Opposite the recess 41 on the hinge block 16 is a corresponding recess 44 also adapted to embrace the roller 42 when the block 16 moves upwardly during a closing operation.

WVhen the block 16 is in its extreme upper position as shown in Fig. 2, it is prevented from going any farther by contact of the parts just described and the abutting faces 45 and 46 on the piston 27 and the cylinder 30 respectively. I make these parts extremely strong because the upward pressure of the block 16, when the bucket is loaded, is very great-in the particular bucket illustrated about 80,000 pounds.

The surfaces 41 and 44 turn slightly about the roller 42 as the block 16 passes from the position shown in Fig. 1 to that shown in Fig. 2 and I prefer, of course, to keep these surfaces well lubricated.

It will be seen that the construction of the abutting parts of this shock absorbing mechanism just described 'is such as to retain the dashpot in proper position to act as a stop when the hinge block 16 finally reachesits uppermost position, the recessed surfaces 41 and 44 preventing displacement of the lower end of the cylinder 30.

The interior of the dashpot is filled with oil which, during upward movement of the block 16, can pass but slowly from the lower side of the piston to the upper side through the passageway 47 in which is inserted a plug 48, provided with a very small hole 49, the size of which, of course, determines the resistance to the flow of the oil in a mannerwell understood in this art, and consequently to the motion of the parts. 7

When the cylinder moves in the opposite direction, the oil returns from the upper side of the piston to the lower side through thelarge capacity return passage 50 in the form of an outside pi e as best shown in Fig. 4, in which is locate the check valve 51 opening in the direction of the arrow 52. The dash pot may be filled with oil through a suitably plugged opening 53.

It will be seen from the foregoing that I have provided a shock absorbing mechanism which will act not only to retard or cushion sudden upward movement of the hinge block, but also to stop such movement when the parts come to their final position as shown in Fig. 2. In this way I have provided a construction which prevents shockl within the bucket structure itself, as well as to the operating cable and crane by virture of the fact that the dashpot cushions the final upward movement of the hinge block 16 and prevents a sudden drop of the bucket. The crane, therefore, although entirely outside of the bucket and independent thereof, is protected by means of structure contained within the bucket itself. At the same time, it should be noted that the use of the dashpot does not impair or lessen the closingpower of the cable because in normal operation the closing motion is not ordinarily so rapid as to place the dashopt into action.

What I claim is 1. A single line bucket having a bucket head and a hinge block characterized by the fact that when the bucket is suspended by its cable with the scoops not quite in their fully closed position, a shock absorbing energy consuming means is provided for retarding the final upward movement of the hinge block into said fully closed position, said shock absorbing means being adapted to act afterwards as a stop for limiting the upward movement of the hinge block.

2. A single line bucket having a bucket head and a hinge block characterized by the fact that there is provided a shock absorbing energy consuming means reacting between the bucket head and the hinge block to retard any final closing movement of the hinge block hinge block, and means for positioning the dashpot. V V v r 4. A shock absorbing device for a single line bucket including in combination with the bucket head and the hinge block, a dashpot mechanism the piston rod of which is pivoted on the bucket head and the cylinder of which is adjustably'and yieldingly supported from the head, engagement means be tween the hinge block and the cylinder, and

abutment means between the piston and the cylinder whereby the dashpot mechanism acts as a stop to limit upward movement of the hinge block when the bucket hingev is dropped.

5. In a single line bucket having a bucket head and a hinge block, a shock absorbing dashpot between'the bucket head and the hinge block, together with abutment means between the piston of the dashpot and its cylinder whereby the dashpot acts as a stop to limit upward movement of the hinge block when the bucket hinge is dropped.

6. A shock absorbing device for a single line'bucket including in .combinationwith the bucket head andthe hinge block, a dashpot mechanism the piston rod of which is pivoted on the bucket head and the cylinder of which is adjustably and yieldingly supported from the head, and engagement means between the hinge block and the cylinder adapted to prevent displacement of the dashpot during compression.

7 In a single line bucket, the combination with the bucket head of a hinge block, a dashpot pivoted on the bucket head and adapted to cushion upward movement of the hinge block, and engagement means between the hinge block and the dashpot adapted to prevent displacement of the dashpot during compression.

8. In a single line bucket, the combination with the bucket head of a hinge block, a dashpot pivoted on the bucket head and adapted to cushion upward movement of the hinge block,

means for positioning the dashpot, and ens gagement means between the hinge block and the dashpot adapted to prevent displace ment of the dashpot during compression.

9. A single line bucket having a bucket is head and a hinge block characterized by the fact that there is provided a liquid containing dashpot mechanism adapted, when the bucket is suspended by its cable with the scoops not quite in their fully closed position, to retard sudden fi'nalupward' movement of the hinge blockand thereby prevent shock.

10. A single line bucket having a bucket head and a hingle block characterized by the fact that there is provided a liquid containing dashpot mechanism reacting between the bucket head and the hinge block to retard the speed of a sudden final upward movement of the hinge block and thereby prevent shock.

In testimony whereof I have hereunto signed my name.

WILLIAM MAYO VENABLE. 

